Study on the influence of sliding structural zone on grouting reinforcement effect of limestone aquifer in coal mine

In this paper, the influence of sliding structural zone on grouting reinforcement effect of limestone aquifer in coal mine is studied. The study area is located in a large coal field in North China, China, with complex geological structure and widely distributed sliding structural zones, which destroyed the integrity of rock strata and increased the risk of water disaster. In this study, ordinary portland cement and polyurethane chemical slurry are selected as grouting materials, and their performance parameters are determined through experiments. The grouting pressure is controlled at 2-4MPa, and the arrangement of grouting holes varies according to different regions. The experimental results show that grouting reinforcement significantly improves the characteristics of limestone aquifer. The permeability is reduced by 75% from 5.2×10-5m/s, and the fluctuation of water level is reduced to 0.1m/d, which proves that the water-blocking curtain is effectively formed and the water-rich property and water conductivity are reduced. At the same time, the compressive strength of rock stratum increased from 25MPa to 38MPa, an increase of 52%, which enhanced the stability and strength of stratum. However, the characteristics of the sliding structural zone affect the reinforcement effect. In the fractured zone, although the grouting material spreads widely, the curing effect is poor, and the compressive strength of the added solid is 32MPa. However, in the stress concentration area of the fold shaft, the curing effect is good, and the average compressive strength reaches 39MPa. The characteristics of rock surface, such as scratches and mirror surface, also affect the adhesion and curing effect. The former has strong adhesion, while the latter has poor adhesion due to smooth surface. In addition, moderate grouting pressure (2-3MPa) and selective use of polyurethane chemical slurry improve the permeability and curing effect in specially developed cracks, while excessive pressure or poor permeability will limit the diffusion and curing effect of grouting materials.